1. Field of the Invention
The present invention relates to monoclonal antibodies binding specifically to a certain serine protease, i.e., neurosin. It also relates to a production process thereof and a method for diagnosing various diseases using the monoclonal antibodies.
2. Disclosure of the Prior Art
In general, proteases are biosynthesized as inactive precursors. They undergo limited hydrolysis in molecules to convert into activated type proteases. In so far as enzymes are proteases, they have an activity for hydrolyzing a peptide bond. However, their action modes are varied according to kinds of proteases. According to particular kinds of catalytic sites, proteases are divided into serine proteases, cysteine proteases, aspartate proteases, metal proteases and the like. Proteases of each kind have a variety of properties such as, from that having general digestive properties to that having various regulatory domains and strict substrate specificity, thereby specifically hydrolyzing only characteristic proteins.
The optimal pH range of serine proteases is neutral to weak alkaline and, in general, many of them have a molecular weight of about 30,000 or lower. All proteases of blood coagulation, fibrinolysis and complement systems which have a large molecular weight belong to trypsin-like serine proteases. They have many regulator domains and form a protease cascade which is very important to reactions in a living body.
According to their primary structure, serine proteases can be divided into subtilisin family and chymotrypsin family. Those of subtilisin family are produced by only Bacillus subtilis, while those of chymotrypsin family are widespread in microorganisms, animals and plants. His-57, Asp-102 and Ser-195 (chymotrypsin Nos.) are concerned in their catalytic activity and, in general, they are inactivated by diisopropyl fluorophosphate (DFP). For exhibiting their activity, a catalytic triad is required, in which His influenced by Asp deprives Ser-195 of its proton to activate Ser. Further, it binds to a substrate to cause polarization of the carbonyl group, and the oxygen atom forms oxy anion. Trypsin has Asn-189 at this site and interacts with the positive charge of a basic amino acid such as Lys, Arg or the like. On the other hand, the corresponding site of chymotrypsin is Ser-189, and an aromatic amino acid such as Tyr, Phe, Trp or the like, or Leu or Met can also bind thereto. In analogy with chymotrypsin, esterase has Ser-189 and interacts with a non-aromatic amino acid such as Ala or the like. As other enzymes belonging to chymotrypsin family, there are Achromobacter protease, plasmin, medullasin, acrosin, V8protease, cathepsin G, chymase, proline specific endopeptidase, submaxillary gland protease A, XIIa, XIa, plasma kallikrein, IXa, Xa, xcex1-thrombin, VIIa, protein C, tissue plasminogen activator, urokinase, C1r, C1s, C2, B, D, I, xcex3-seminoprotein, tissue kallikrein, C and B factors of Limulus polyphemus blood cells, blood coagulation enzymes and the like.
Recently, cDNA and amino acid sequences of many novel proteases have been determined by PCR using oligonucleotide primers for consensus sequences of serine proteases. According to this method, novel proteases have been found by various researchers such as Yamamura et al. (Yamanura, Y et al., Biochem. Biophys. Res. Commun., 239, 386, 1997), Gschwend, et al. (Gschwend, T. P. et al., Mol. Cell. Neurosci., 9. 207, 1997), Chen et al. (Chen, Z-L, et al., J. Neurosci., 15, 5088, 1995) and others.
SEQ ID NO: 3 of JP 9-149790 A discloses neurosin as a novel serine protease. Neurosin has also been reported in Biochimica et Byophysica Acta, 1350, 11-14, 1997. Neurosin having not more than 30% identity to known serine proteases has been obtained as a result of recognition of serine protease activity in a culture supernatant of human colon cancer COLO201 cells and isolation of a cDNA encoding neurosin. By this, there is provided a method for mass production of neurosin using the serine protease gene and a method for screening specific inhibitors using the enzyme. In addition, the screening method has been shown to be useful for screening medicines for treating various diseases.
At present, functions of neurosin are still unknown. However, since neurosin is abundantly expressed in brain, it is presumed to play an important role in maintenance of brain functions. Further, there is a possibility that further detailed functions can be elucidated by using recombinant protein.
JP 6-62855 A discloses a novel serine protease, Zyme, and this is also reported by J. Biol. Chem., 272(40), 25135-2514, 1997. The cDNA and amino acid sequences of Zyme have been determined by PCR amplification of consensus sequences having chymotrypsin-like activity to construct a cDNA library by using the brain mRNA of a patient with Alzheimer""s disease. The mRNA encoding Zyme is recognized in several mammals. Further, although Zyme is expressed abundantly in brain, kidney and salivary glands, as to brain, it is not expressed in fetal brain, but is expressed only in adult brain. Further, Zyme has a gene in chromosome 19q13.3, and this region has been revealed to be a part linking to late onset familial Alzheimer""s disease. Then, it is considered that Zyme would be useful for elucidating characteristics of neural diseases such as Alzheimer""s disease and Down""s syndromes.
WO 98/11238 discloses a novel protease, Protease M, and this is also reported in Molecular Medicine, 2(5), 624-636, 1996. Protease M cDNA is obtained from normal human mammary epithelial 76 N cell line and has a sequence very similar to kallikrein, Prostate-Specific Antigen (PSA) and trypsin. And, Protease M gene is present in chromosome 19q13.3. Protease M is considered to be a marker useful for primary breast adenocarcinoma and primary ovary cancer because, while it is downregulated in metastatic breast cancer cell line, its mRNA is strongly expressed in primary breast cancer cell line, ovary cancer tissue and cancer cell line.
Although origins of these neurosin, Zyme and Protease M are different, their cDNA sequences and amino acid sequences, and further the positions in chromosome conformation of the genes encoding them are completely identical to one another. Since there is a high possibility that these substances would be the same substance, the name xe2x80x9cneurosinxe2x80x9d is used herein to refer to them altogether. As described above, this serine protease has been found by different groups of researchers almost at the same time, and its pharmacological activities have been studied. Then, it is expected that its importance will be elucidated on various occasions in the future. For example, Games et al. (Games, D. et al., Nature, 373, 523, 1995) and Hsiao et al. (Hsiao, K, et al., Science, 274, 99, 1996) succeeded in expression of a large amount of xcex2-amyloid precursor protein (xcex2APP), and production of transgenic mice in which deposition of amyloid xcex2 protein (Axcex2) was observed in 1995 and 1996, respectively. Then, the role of the above serine protease in Alzheimer""s disease and the like will be further elucidated in the future.
As disclosed in JP 6-62855 A, Zyme (i.e., neurosin) plays an important role in Alzheimer""s disease and Down""s syndromes. While it has been proposed that Alzheimer""s disease should be divided into that presenile Alzheimer""s disease and Alzheimer type senile dementia manifesting in senescence from the pathological viewpoint, the term xe2x80x9cAlzheimer""s diseasexe2x80x9d is used herein to refer to them altogether.
Clinically, Alzheimer""s disease is characterized by progressive decline of various recognition functions and the main neuropathological observation is to find abnormal structures such as senile plaque and neurofibril change in addition to nerve cell degeneration and deficiency (Trojanowski, J. Q. et al., In Current Neruology, 16, 93, 1996). Among them, while senile plaque also appears in case of normal aging, it appears much more frequently in case of Alzheimer""s disease and is a pathological observation having high disease specificity. Further, xcex2-amyloidogenesis can be said to be a most important subject to be elucidated from the pathogenic viewpoint because, for example, the deposition of Axcex2 which is a constituent component of senile plaque is the earliest pathological observation in brain of Alzheimer""s disease, and further familial Alzheimer""s disease having point mutation in xcex2APP gene which is the precursor of Axcex2 has been found.
In Down""s syndromes wherein the 21st chromosome having xcex2APP is a trisomy, the same pathological observation in brain as that of Alzheimer""s disease is found in all cases after age thirty. Teller et al. (Teller, J. K. et al., Nature Med., 2, 93, 1996) have reported that soluble Axcex21-42 increases in proportion to age and density of senile plaque on the basis of the results of determination of soluble Axcex2 extracted from brains of patients with Down""s syndrome, aged from fetal to in their sixties, by immunoprecipitation and western blotting. In addition, they have suggested that the increase in soluble Axcex2 is concerned with excess production of xcex2APP and formation of senile plaque because soluble Axcex2 is found even in cases of juvenile Down""s syndrome wherein no senile plaque is present, while it is not observed in a control group. Further, Tokuda et al. (Tokuda, T. et al., Ann. Neurol., 41, 271, 1997) have reported that the significant increase in both plasma Axcex21-40 and Axcex21-42 (43) in a group with Down""s syndrome is found in comparison with that of a control group. In view of these facts, there is a possibility that neurosin would have a certain action on Down""s syndrome.
Further, neurosin is also considered to have a certain action on dementia pugilistica and diffuse Lewy bodies disease which are closely related to Alzheimer""s disease.
Senile plaque is a spot structure having 50 to 200 xcexcm diameter which mainly appears in cerebral cortex of brain with Alzheimer""s disease. Senile plaque after passage of time has an amyloid core in the center and accumulation of degenerated axons and reactive glia cells are observed about it. Axcex2 is polymerized in the form of a xcex2 sheet structure to form amyloid fiber. In general, it is considered that the extracellularly polymerized amyloid Axcex2 is toxic to nerve cells (Yankner, B. A. et al., Science, 250, 279, 1990; Simmons, L. K. et al., Mol. Pharmacol., 45, 373, 1994). Axcex2 is a main component of the amyloid core which has a molecular weight of about 4 kDa and is composed of about 42 amino acids. In addition to senile plaque, it accumulates in small blood vessels in meninx and cortex to form amyloid angiosis. Kang et al. (Kang et al., Nature, 325, 733, 1987) have showed that Axcex2 is derived from the larger precursor, xcex2APP, by cloning based on the information of the amino acid sequence of Axcex2 revealed by Glenner et al. (Glenner, G. G. and Wong, C. W., Biochem. Biophys. Res. Commun., 120, 185, 1984).
xcex2APP is a glycoprotein having a structure similar to that of a transmembrane receptor and having a molecular weight of 120,000 to 130,000. Axcex2 is integrated in the region from the transmembrane domain through the extracellular domain of xcex2APP. At present, 6 kinds of xcex2APP have been identified. As the identified xcex2APP which is concerned in amyloid deposition, there are xcex2APP659 which is predominantly expressed in brain (Kang, J. et al., Proc. Natl. Acad. Sci., 82, 4245, 1985), xcex2APP751 which has an amino acid region composed of 56 amino acids homologous to a serine protease inhibitor of Kuntiz family, xcex2APP770 which has an amino acid region composed of 19 amino acids homologous to MRC X-2 antigen, and the like. xcex2APP751 and xcex2APP770 are predominantly expressed in whole body organs. Since all of them have Axcex2 part at the 99th amino acid from the C-terminus, they are considered to be concerned in amyloid formation in brain.
While physiological functions of xcex2APP are still unknown, xcex2APP expressed in cell surfaces, or soluble xcex2APP which are cleaved in Axcex2 domain and released from cells has been reported to act extracellularly as a cell adhesion molecule (Schubert, D. and Behl, C., Brain Res., 629, 275, 1993), or a certain nutriment factor (Saitoh, T. et al., Cell, 58, 615, 1989). On the other hand, xcex2APP is presumed to be carried to the end of axon with an axonal flow, followed by expression in synaptic membrane, thereby playing an important role in synapse formation or its maintenance in nerve cells (Schubert, W. et al., Brain Res., 563, 184, 1991).
As to metabolism of xcex2APP, in general, two pathways are presumed. That is, one is a secretion pathway wherein Axcex2 domain is cleaved at the center thereof with so-called xcex1-secretase and its N-terminus product is released to outside of cells. The other is endosomal-lysosomal pathway wherein xcex2APP is incorporated in cells directly or after once expressed on cell surfaces and, finally, it is decomposed in lysosomes. Although the region in which Axcex2 is produced during these xcex2APP metabolism pathways is still unknown, one possibility which can be presumed is that Axcex2 is cut out immediately after incorporation of xcex2APP in endocytic vesicle and is released to outside of cells immediately (Koo, E. H. and Squazzo, S. L., J. Biol. Chem., 269, 17386, 1994).
After discovery of Axcex2, it was considered that cut out of Axcex2 was caused only in a disease state. However, the later studies have revealed that Axcex2 is produced physiologically and is present in the soluble state in a culture supernatant (Haass, C. et al., Nature, 359, 322, 1992; Shoji, M. et al., Science, 258, 126, 1992) or in cerebrospinal fluid (Shoji, M. et al., Science, 258, 126, 1992; Seubert, P. et al., Nature, 359, 325, 1992). For cutting out of Axcex2 from xcex2APP, an enzyme for cleaving the N-terminus side of Axcex2 (xcex2-secretase) and an enzyme for cleaving the C-terminus side of Axcex2 (xcex3-secretase) are required (Haass, C. et al.; Cell, 75, 1039, 1993). While these secretases of Axcex2 are not yet identified, recently, it has been revealed that cleavage with xcex2-secretase strictly depends on the amino acid sequence (Citron, M. et al., Neuron, 14, 661, 1995).
At present, for example, cathepsin B which is a cysteine protease (Tagawa, K. et al., Biochem. Biophys. Res. Commun., 177, 377, 1991) and metalloprotease having a molecular weight of 105 to 120 kDa (McDermott, J. R. et al., Biochem. Biophys. Res. Commun., 179, 1148, 1991) are reported to be candidates for xcex1-secretase. Prolyl endopeptidase (Ishiura, S. et al., FEBS Lett., 260, 131, 1990) is reported to be a candidate for xcex3-secretase. Clipsin (Nelson, R. B. et al., J. Biol. Chem., 265, 3836, 1990) and ingensin (Ishiura, S. et al., FEBS Lett., 257, 388, 1989) are reported to be candidates for xcex2-secretase.
Under these circumstances, it has been found neurosin as a novel serine protease which cleaves the N-terminus side of xcex2APP at between Met596 and Asp597 to produce Axcex2. As described above, for conducting more detailed studies of Axcex2 and xcex2APP as well as Alzheimer""s disease and Down""s syndromes, a measuring system of neurosin is essentially required.
Nowadays, in general, clinical diagnosis of Alzheimer""s disease is conducted based on the diagnosis standard of DSM-IIIR and NINCDS-ADRDA (Mckhann, G. et al., Neurology, 34. 939, 1994) or the diagnosis standard of DSM-IV (American Psychiatric Association; Diagnostic and statistical manuals of mental disorders, 4th ed., Washington D.C., American Psychiatric Association, 1994). However, these standards are conditioned by decline of recognition functions which causes a severe disability in a daily life or a social life. Then, it is pointed out that the diagnosis is less scientific objectivity because the diagnosis may be influenced by the level of an individual""s social life and further the specialty and experience of a physician who diagnoses particular conditions. In addition, definite diagnosis of Alzheimer""s disease is conducted by pathohistological analyses and, in this respect, substantial inconsistency between clinical diagnosis and autopsy diagnosis is pointed out.
At present, image diagnosis is employed as a supplemental means in clinical diagnosis of Alzheimer""s diagnosis and it is possible to analyze brain functions, for example, decline of metabolism and atrophy in specific sites such as hippocampus, parietal lobe of cerebral cortex and the like which are specific for Alzheimer""s disease by PET and SPECT (Fukuyama, H. et al., J. Nucl. Med., 35, 1, 1994). While it is difficult to analyze many cases by PET, there is a report showing that lowering of a blood flow from parietal lobe to temporal lobe is observed in about 80% of Alzheimer""s disease cases based on SPECT data of blood flow observations in many cases (Haruo HANYUU, et al., Gazoshindan of Alzheimer""s Disease, Nippon Ronen Igaku Zasshi, 31, 683, 1994). However, to define Alzheimer""s disease based on lowering of a blood flow from parietal lobe to temporal lobe is very dangerous and it should be noted that, lowering of a blood flow in frontal lobe is found in some remaining cases. As to these observations, to differentiate Alzheimer""s disease from degenerative cerebral atrophy such as Pick""s disease and progressive aphasia as well as progressive supranuclear palsy is of importance, and only presently available reliable way is pathological diagnosis.
Further, while useful observations to be used for malignant tumor, angiopathy, diseases with metabolic change are obtained by MRS (Magnetic Resonance Spectroscopy) analyses, few reports are found with respect to patients with dementia including Alzheimer""s disease. In particular, at present, a characteristic observation of dementia cannot be detected by 1H-MRS because of overlap with encephalatorophy observation such as the decrease in NAA (N-acetyl-aspartate) peak (Pettegrew, J. W. et al., J. Neuropathol., Exp., Neurol., 46, 419, 1987; Barany, M. et al., Lancet, i, 517, 1985; Smith, L. et al., Book of Abstracts, Society of Magnetic Resonance in Medicine 1986, Vol. 4, Berkeley, Society of Magnetic Resonance, 1386, 1986).
Furthermore, CT-MRI image diagnosis is used. By CT, one can observe localized atrophy weighted at temporal lobe and parietal lobe, and progressive generalized atrophy, as well as ventricular enlargement and periventricular low density (PVL) or change of white matter about ventricle called as leuko-araiosis in parallel with atrophy. However, white matter lesions such as atrophy of brain, PVL and the like are not specific characteristics of Alzheimer type dementia. Further, progress of atrophy of brain with aging is reported (Barron, S. A. et al., Neurology, 26, 1011, 1976; Zatz, L. M. et al., AJNR, 3, 1, 1982). Then, these observations are not necessarily found in Alzheimer type dementia.
MRI is very useful because, in particular, each site of brain can be observed at any imaging plane and can confirm presence of microangiopathy and the like which cannot be found out by X-ray CT. As to Alzheimer""s disease, when imaging at an axial section and an arrowy section as well as a coronal section, observations which are overlooked by CT can be obtained. First, it has been found that atrophy of corpus callosum can be observed by imaging at an arrowy section from an early stage of the disease and it has been possible to conduct detailed observation of temporal lobe including hippocampus by imaging at coronal section. Further, in observation of brain parenchyma, cinerea can be readily differentiated from white matter by a proton weighted image. However, since an image obtained by MRI varies according to strength of a magnetic field, performance of an apparatus and imaging conditions, numerical data obtain in different facilities cannot be compared with each other except atrophic change. In addition, there is a limit to image measurement. Although area measurement is considered to be more sensitive than linear one and volume measurement is considered to be more sensitive than area measurement, it is difficult to conduct such measurement routinely. Further, enlargement of ventricle can be recognized in vascular dementia cases and there are cases wherein atrophy of hippocampus is observed after ischemia of basilar artery.
Under these circumstances, many researchers have requested to develop biological diagnosis markers as a means for providing better precision and objectivity for clinical diagnosis of Alzheimer""s disease. At the same time, the following important roles in the future will be expected.
1) Objective judgment system of effect of medicaments for treating Alzheimer""s disease.
2) Detection of Alzheimer""s disease before a diagnosis standard is met, or disease conditions are manifested.
Further, data obtained in different facilities can be compared with each other by using the same diagnosis marker. Therefore, development of biological diagnosis markers is recognized to be a most important field among fields of Alzheimer""s disease studies and its future prospects will be expected.
In general, approaches to development of biological diagnosis markers up to now are divided into that based on constitute components of characteristic pathological changes of Alzheimer""s disease such as senile plaque and neurofibril change, and an approach based on other measures. Examples of the former include cerebrospinal fluid tau protein, Axcex2 and its precursor, xcex2APP. Examples of the latter include mydriasis test with cholilytic drug, Apo E and other genes relating to Alzheimer""s disease. However, no good results are obtained.
The present inventors have expected that, from now, various brain diseases (e.g., Alzheimer""s disease, Down""s syndromes, etc.) can be identified by utilizing secretion of neurosin, whose expression is recognized in brain. in cerebrospinal fluid which is a useful sample for physiological studies of brain, and that secretion of neurosin can be used as an effective biological diagnosis marker even at an early stage of brain diseases . For this, a neurosin measurement system is also essential.
As described in WO98/11238, Protease M (i.e., neurosin) also plays an important role in cancer cells. The reason why extermination of cancer by surgical treatment or topical irradiation of radioactive ray is difficult is metastasis capability of cancer. For spread of solid tumor cells in a body, they should loosen their adhesion to original adjacent cells, followed by separating from an original tissue, passing through other tissues to reach blood vessel or lymph node, entering into the circulatory system through stratum basal and endothelial layer of the vessel, leave from the circulatory system at somewhere in the body, and surviving and proliferating in a new environment. While adhesion to adjacent epidermal cells is lost when expression of cadherin which is an intercellular adhesive molecule of epithelium is stopped, to break through tissues is considered to depend on proteolytic enzymes which decompose an extracellular matrix. As enzymes which decompose the matrix, mainly, metal proteases (Rha, S. Y. et al., Breast Cancer Research Treatment, 43, 175, 1997) and serine proteases are known. They cooperate to decompose matrix protein such as collagen, laminin and fibronectin. Among serine proteases known to be concerned in decomposition of the matrix, in particular, there is urokinase type plasminogen activator (U-PA) (Kinojo, M. et al., Br. J. Cancer, 39, 15, 1979; Danl, K. et al., Adv. Cancer Res., 44, 146, 1985; Nakanishi, K. et al., Cancer, 82, 724, 1998; Shiba, E. et al., J. Cancer Res. Clin. Oncology, 123, 555, 1997). U-PA has a role as a trigger specific for a protein decomposition chain reaction. Its direct target is plasminogen. It is present in blood abundantly and is a precursor of an inactive serine protease which accumulates in reconstructed sites of tissues such as injured sites and tumors as well as inflammatory sites. In addition, as proteases which are concerned in metastasis and infiltration of cancers, for example, a tissue factor (Kinjo, M. et al., Br. J. Cancer, 39, 15, 1979), lysosomal type hydrolase (Sloane, b. f. et al., Cancer Res., 42, 980, 1982) and collagenase (Mignatti, P. et al., Cell, 47, 487, 1986) have been known.
At present, cancer is the top cause of death in Japan and more than 200,000 people die per year. Then, specific substances which can be used as markers for diagnosis and therapy or prophylaxis of cancer is studied intensively. Such specific substances are referred to as tumor markers or tumor marker relating biomarkers. They are utilized in aid of diagnosis before treatment of cancer, for presuming carcinogenic organ and pathological tissue type, for monitoring effect of treatment, for finding recurrence early, for presuming prognosis, and the like. At present, tumor markers are essential in clinical analyses. Among them, alpha fetoprotein (AFP) which has high specificity to hepatocellular carcinoma and yolk sac tumor (Taketa K. et al., Tumour Biol., 9, 110, 1988), and carcinoembronic antigen (CEA) are used worldwide. In the future, tumor markers will be required more and more, and it is desired to develop, for example, organ specific markers and tumor cell specific markers which are highly reliable serologic diagnosis of cancer.
Up to now, human glandular kallikrein (hK2) which is a serine protease expressed at human prostatic epithelial cells has been reported as a marker for prostatic cancer. And, hK2 has 78% homology with the sequence of prostatic specific antigen (PSA) and PSA is also used widely as a biochemical marker of prostatic cancer (Mikolajczyk, S. d. et al., Prostate, 34, 44, 1998; Pannek, J. et al., Oncology, 11, 1273, 1997; Chu, T. M. et al., Tumour Biology, 18, 123, 1997; Hsieh, M. et al., Cancer Res., 57, 2651, 1997). Further, hK2 is reported to be useful as a marker for not only prostatic cancer but also stomach cancer (Cho, J. Y. et al.. Cancer, 79, 878, 1997).
Moreover, CYFRA (CYFRA 21-1) for measuring cytokeratin 19 fragment in serum is reported to be useful for lung cancer (Sugiyama, Y. et al., Japan J. Cancer Res., 85, 1178, 1994). Gastrin release peptide precursor (ProGRP) is reported to be useful as a tumor marker (Yamaguchi, K. et al., Japan, J. Cancer Res., 86, 698, 1995). Therefore, it is expected that combination of CYFRA and ProGRP may become a very useful means in aid of diagnosis for early diagnosis of lung cancer.
In particular, tumor markers are frequently used in diagnosis of ovarian cancer because, for example, ovarian cancer is difficult to find out at an early stage, is found out in its progressed state in many cases, has many varieties of tissue types, is difficult to presume the tissue type only by image diagnosis, is seldom benign ovarian tumor, and is required to differentiate from malignant one. At present, for example, CA125 which is a sugar chain relating antigen is used as a tumor marker of ovarian cancer clinically. However, it has been revealed that the average value of CA125 of a healthy person decreases with aging or after menopause. Then, it is required and desired to develop a marker which reinforces the weakness of CA125. In addition, for breast cancer, for example, CEA, TPA and CA15-3 are used. However, they are far from excellent markers in view of sensitivity and specificity and are insufficient for early diagnosis.
Under these circumstances, a serine protease, neurosin, which can be used as a marker for early breast cancer and early ovarian cancer has been found out. As described above, a measurement system of the serine protease, i.e., neurosin is essential for further detailed studies of metastasis and infiltration mechanism of cancer. In addition, from now, it is expected to be a biological diagnosis marker which can identify early ovarian cancer and early breast cancer, as well as can effectively diagnose them. For this, a neurosin measuring system is also desired.
Furthermore, although WO98/11238 describes a monoclonal antibody, in fact, no hybridoma is actually produced and no monoclonal antibody having specificity to a serine protease is actually obtained. Although this document discloses that the monoclonal antibody can be produced by known techniques, it is uncertain whether a hybridoma producing a monoclonal antibody specifically binding to a serine protease can be obtained in a screening step of hybridomas, or not.
In view of the above circumstances, the present inventors have undertaken the production of a monoclonal antibody specifically binding to a serine protease.
Thus, the main object of the present invention is to provide a monoclonal antibody specifically binding to neurosin which can be used for measuring the serine protease, neurosin.
This object as well as other objects and advantages of the present invention will become apparent to those skilled in the art from the following description with reference to the accompanying drawings.